Pension and Other Postretirement Benefits - Summary of Accumulated Other Comprehensive Loss, Changes in these Amounts and Expected Amortization of these Amounts as Components of Net Periodic Benefit Cost (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014
Pension Benefits [Member]
Pension And Other Employee Benefit Plans [Line Items]
Net actuarial loss, beginning of year	$ 46,468
Net actuarial loss	61,333
Amortization cost	(4,154)
Net prior service credit	(94)
Actuarial loss (gain)	28,971
Total	61,239
Asset gain	(7,755)
Currency impact	(2,197)
Net actuarial loss, end of year	61,333
Prior service credit, beginning of year	(106)
Amortization credit	48
Currency impact	(36)
Prior service credit, end of year	(94)
Amortization of prior service credit	(41)
Amortization of net loss	5,319
Total	5,278
Other Benefits [Member]
Pension And Other Employee Benefit Plans [Line Items]
Net actuarial loss, beginning of year	9,622
Net actuarial loss	4,679
Amortization cost	(315)
Net prior service credit	(143)
Actuarial loss (gain)	(4,392)
Total	4,536
Asset gain	0
Currency impact	(236)
Net actuarial loss, end of year	4,679
Prior service credit, beginning of year	(259)
Amortization credit	100
Currency impact	16
Prior service credit, end of year	(143)
Amortization of prior service credit	(95)
Amortization of net loss	354
Total	$ 259